Symmetric serrated edge light guide film having elliptical base segments
a light guide film and elliptical base technology, which is applied in the direction of optical waveguide light guide, lighting and heating apparatus, lighting device details, etc., can solve the problem of limited light diffusing capability of continuous prism or arc-shaped structures on the input surfa
Inactive Publication Date: 2013-01-03
SKC HAAS DISPLAY FILMS CO LTD
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Benefits of technology
The present invention provides a planar light guide film for a backlight unit that has at least one point light source. The light guide film has a light input surface, a light redirecting surface, and a light output surface for outputting the redirected light. The light input surface has a unique composite lens structure, while the light redirecting surface has a unique serrated lens structure. The composite lens structure and serrated lens structure have specific shapes and sizes to redirect the light from the point light source efficiently. This results in a brighter and more uniform light output from the backlight unit.
Problems solved by technology
Thus the continuous prism- or arc-shaped structures on the input surface have limited light diffusing capability.
Method used
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[0046]FIG. 9a shows a portion of the light input surface 32 of a light guide film 30 with an arc- or circular-type structure 36. The graph in FIG. 9b illustrates the light intensity for the light guide film 30 at distances 3.5 mm, 4.5 mm and 5.5 mm from the light input surface 32. FIG. 9b shows that the localized light intensity decreases as the distance increases from the light input surface, but there are still some hot spots evident at 5.5 mm The arc- or circular-type structure solution provides some improvement for hot spots but is more effective at collimating light in line with the LED than widening the incidence angle. This is evident in the graph in FIG. 9b. In FIG. 9b, the LEDs are located at each of the vertical dotted lines and the light distribution is still not leveled out at 5.5 mm into the light guide film. It is apparent from the graph in FIG. 9b that the arc- or circular-type solution has insufficient diffusion capability.
[0047]FIG. 10a shows a portion of the light ...
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The present invention provides a planar light guide film for a backlight unit having at least one point light source, the light guide film comprising a light input surface for receiving light from the point light source, a light redirecting surface for redirecting light received from the light input surface and a light output surface for outputting at least the light redirected from the light redirecting surface. The light input surface further comprises a composite lens structure having a circular tip segment with a first contact angle, and a first and second elliptical base segments with a second contact angle, the second contact angle being less than the first contact angle and the second contact angle being equal to each other andwherein the circular tip segment satisfies the following equation:y1=a1+√{square root over ((r12−x2))}and the elliptical base segments satisfies the following equations:y4=d4+b4×√{square root over ((1−((x+c4) / a4)2)}y5=d5+b5×√{square root over ((1−((x−c5) / a5)2)}
Description
FIELD OF THE INVENTION[0001]The present invention relates to a light guide film of a light emitting diode (LED) backlight unit, and, more particularly, to a light guide film of an LED backlight unit, which has a plurality of grooves carved into an incident plane of the light guide film to increase an incidence angle of which light can be transmitted through the light guide film.BACKGROUND OF THE INVENTION[0002]Typically, a liquid crystal display (LCD) for handheld and notebook devices generally employs at least one lateral light emitting diode (LED) as a light source of a backlight unit. Such a lateral LED is generally provided to the backlight unit as shown in FIG. 1 of Yang U.S. Pat. No. 7,350,958.[0003]Referring to FIG. 1, the backlight unit 10 comprises a planar light guide film 20 disposed on a substrate 12, and a plurality of lateral LEDs 30 (only one lateral LED is shown in FIG. 1) disposed in an array on a lateral side of the light guide film 20. Light L entering the light g...
Claims
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IPC IPC(8): G02B6/10
CPCG02B6/002G02B6/0016
Inventor HONG, QIMALBURNE, KAREN A.
Owner SKC HAAS DISPLAY FILMS CO LTD